Another issue seems to be getting more common on the 400s. The rubber seal for the coolant passage between the crankcase and the cylinder jug can deform, causing a small coolant leak on the front of the engine.
It's not a huge catastrophic failure, but it's labor-intensive to replace. Some people have reported their dealerships getting Kawasaki to cover the repair even after the warranty has ended.
Once again, Jesse to the rescue with the
Norton Racing Replacement Cylinder Coolant Seal. Rather than just being a rubber O-ring, it's a machined aluminum body with captive O-rings on top and bottom, to provide seals on both surfaces without any deforming worries.
This isn't really something you'd replace preventatively on a street bike (due to the labor involved for a problem you might never run into), but you may want to on a race bike where you can't accept failure and/or are already doing engine work. If you've run into this problem and are repairing it, you should definitely look into this upgrade. The OEM part (92055-0888) is only about $4 vs. $40 for the Norton part, but $36 is going to be a drop in the bucket of the overall cost of this repair, especially if you have to do it a second time due to another failed OEM O-ring later on.